Jobe’s makes slow-release fertilizer spikes that deliver nutrients directly to tree roots without the mess, mixing, or runoff of liquid fertilizers. That’s the whole pitch. Season-long feeding from a single application, which matters when Montana’s growing season runs maybe five months if you’re lucky.
The spikes solve a real problem. Granular fertilizers wash away with spring snowmelt. Liquid fertilizers need multiple applications through the season. These spikes deliver a continuous supply of nutrients below the surface where freeze-thaw cycles can’t touch them.
Technical Specifications Worth Knowing
The evergreen formulation runs 11-3-4 or 13-3-4 NPK ratios — heavy on nitrogen to push that deep green color conifers need after a long winter. Deciduous trees get different ratios: 15-3-3 or 16-4-4 for standard trees and shrubs, while fruit and citrus trees need the 9-12-12 formula with higher phosphorus and potassium for fruit production.
| Product Type | NPK Ratio | Pack Sizes | Duration |
|---|---|---|---|
| Evergreen | 11-3-4, 13-3-4 | 9, 15, 72 spikes | Season-long |
| Tree & Shrub | 15-3-3, 16-4-4 | 5 spikes, 15 spikes | 90 days |
| Fruit/Citrus | 9-12-12 | 5 spikes | Not specified |
Standard packs weigh 2.2 pounds while bulk contractor packs hit 18 pounds with 72 spikes. The bulk option makes sense for commercial properties with multiple trees. Each 5-pack weighs about 4.32 ounces.
Application That Actually Works
Application timing follows Montana’s rhythm: early spring before new growth and late fall after the growing season. Drive them into the ground around the dripline where feeder roots are active. No guessing on dosage — one spike per inch of trunk diameter keeps it simple for bidding jobs.
The slow-release formula feeds all season up to 90 days, which covers most of Montana’s growing window. Pre-measured spikes eliminate over-fertilization risk — a real issue when crews are hitting multiple properties in a day.
The spikes work because they bypass Montana’s specific challenges. Spring application goes in after frost leaves the ground but before trees break dormancy. Nutrients go directly to the root zone, avoiding the surface where late snow or early heat can waste traditional fertilizers. Fall application helps trees harden off for winter without the flush of tender growth that liquid nitrogen causes.
What Contractors Think
Professionals value these spikes for their convenience and targeted root zone application. The slow-release formula reduces application frequency and minimizes runoff — both billing advantages when you’re maintaining commercial properties.
The downside? They won’t fix specific soil deficiencies or pH problems. Compacted or poorly draining soils can limit nutrient movement to roots. If soil tests show major deficiencies, spikes won’t replace proper soil amendment. They’re maintenance fertilizer, not corrective treatment.
Jobe’s operates from Waco, Texas with additional manufacturing in Kentucky, pushing over 200 products into garden centers. The company started in 1969 with houseplant spikes, then expanded to trees and shrubs before Easy Gardener acquired them in 1996. They rebranded as The Jobe’s Company in 2016.
For Montana’s short season and challenging soils, fertilizer spikes make sense. They deliver measured nutrition through the root zone without the hassle of mixing, measuring, or multiple applications. Not magic, but solid engineering that respects how trees actually feed.
Frequently Asked Questions
How many fertilizer spikes per tree? Use one spike per inch of trunk diameter measured at chest height. A 6-inch diameter tree needs 6 spikes driven around the dripline. Bulk packs with 72 spikes handle commercial properties efficiently.
When should tree spikes be applied in Montana? Apply in early spring before new growth starts and again in late fall after the growing season ends. Spring application typically happens in April when soil thaws but before bud break. Fall application runs September-October before ground freezes.
How long do Jobe’s fertilizer spikes last? Tree and shrub spikes feed for up to 90 days. Evergreen spikes are labeled for season-long feeding. In Montana’s climate, one spring application often covers the entire growing season.
Do fertilizer spikes work in clay soil? Spikes may struggle in heavily compacted or poorly draining soils where nutrients can’t reach roots efficiently. Pre-drill holes in heavy clay for better penetration. Consider aerating around trees before application.
What’s the NPK ratio for evergreen spikes? Evergreen formulations run 11-3-4 or 13-3-4 NPK ratios with higher nitrogen for needle retention and color. Compare to 15-3-3 or 16-4-4 ratios for deciduous trees.
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